1. Field of the Invention
The present invention relates to electrical resistance heating cables, and, more particularly, to a crimp splice for an electrical resistance heating cable.
2. Description of the Related Art
Electrical resistance heating cables or traces are known that provide heat for a variety of applications. An electrical resistance heating cable can include a resistive conductor, such as a nickel chromium alloy wire, that for a given gauge cross-section provides a predetermined ohms/ft. and, for a given voltage, a predetermined watts/ft. heat output.
Construction of an electrical resistance heating cable in a coaxial form can include the resistive conductor surrounded by an electrically insulative but thermally conductive insulation. A ground braid can surround the insulation and there can be further insulation around the ground braid.
An application of an electrical resistance heating cable includes floor warming and heating. For example, a commercial floor drying system can use an electrical resistance heating cable to provide radiant heat and imbedded moisture sensors to solve a variety of indoor problems including: cleaning activities, condensation around walk-in freezers and refrigerators, food preparation areas, dishwashing areas, salad bars and sanitary facilities
Other applications include electric pavement, floor or roof snow/ice melting, gutter deicing and freeze protection pipe trace applications. The heating cable can be used with automatic controls and sensors to operate heaters only while needed, based on conditions, to ensure minimal energy consumption, which is also true of previously mentioned applications.
Telecommunications applications of an electrical resistance heating cable or systems can include earth station satellite antenna deicing systems to ensure reliable operation of the antenna and reliable satellite signal reception and/or transmission by the antenna. Another telecommunication application can include broadcast antenna deicing such as for FM broadcast antennas. As with other applications, automatic deicing can be achieved using appropriate controllers and sensors.
IEEE (Institute of Electrical and Electronics Engineers) standard 515.1-1995 provides a recommended practice for the testing, design, installation, and maintenance of electrical resistance heat tracing (cable) for commercial applications. The standard provides specific test requirements for qualifying electrical resistance heating cables for commercial service and a basis for electrical and thermal design. The standard addresses heater characteristics and installation and maintenance requirements, and further, recommendations and requirements for unclassified heating cable applications are provided.
In use, an electrical resistance heating cable can have its two ends stripped of insulation to expose a portion of the resistive conductor at both ends. Each exposed end portion of the resistive conductor can be connected to a standard conductor such as an 18 AWG stranded conductor with insulation, for example, that allows for connection of the electrical resistance heating cable to an electrical power source. As with the resistive conductor, standard conductors typically have ends stripped of insulation to exposed the conductor wire. The ground braid of the electrical resistance heating cable can also be connected to a standard conductor to facilitate connection to ground.
Connection of the exposed end portions of the resistive conductor to the exposed wire of the standard conductors can be achieved by a crimp slice. However, the crimp tooling limits how close the electrical resistance heating cable insulation can be to the end of the standard conductor or the crimp connector. This tooling limitation creates a section of the exposed end portion of the resistive conductor that has an air gap between the resistive conductor insulation and crimped splice or standard conductor. Air can be a relatively poor heat conductor, particularly when compared to the electrical resistance heating cable insulation, and heat can build up in the vicinity of the air gap. Both of the resistive conductor and the electrical resistance heating cable insulation can potentially elevate in temperature, in the vicinity of the air gap, resulting in the resistive conductor going through the insulation and touching the ground braid thereby creating a ground fault, among other problems.
What is needed in the art is a device and method for crimping a resistive conductor of an electrical resistance heating cable to a standard conductor that dissipates heat in the vicinity of the air gap, while allowing for appropriate crimp tooling, and while also allowing safe and reliable construction and operation of the electrical resistance heating cable with compliance to industry standards where appropriate.